Code in posts only gets syntax highlighting in the live preview

[tobyzerner]

Steps to reproduce:

1. Open up the reply composer and enter [code=php]$foo = "bar";[/code]
2. Look at the live preview, and see the syntax highlighting
3. Submit the reply
4. Look at the post, and see no syntax highlighting

Expected behaviour:
The submitted post should have syntax highlighting.

What needs to be done:

• Call typeof hljs !== 'undefined' && hljs.initHighlighting() in CommentPost's config method, but only if the post's contentHtml hasn't changed since the last redraw.